1. Secure computer system: Unified exposition and Multics interpretation;Bell;MITRE MTR-2997,1976
2. available as NTIS AD-A023 588.
3. Best available technologies for computer security;Landwehr;IEEE Comput.,1983
4. Primitive models for computer security;Walter;ESD-TR-74-117,1974
5. available as NTIS AD-778 467.